Driving assistance systems can assist the driver of a vehicle in controlling the vehicle, for example in maneuvering between obstacles, on narrow roads or when parking in a parking space. Driving assistance systems can have sensors for detecting the surroundings, and can give the driver information concerning the driving maneuver conducted by the driver, for example in the form of visual or acoustic signals. Automatic driving assistance systems include those systems which perform not only the detection of information about the surroundings, but also the control of the vehicle, for example when parking. Furthermore, other systems provide for automatically calculating a suitable route and also for executing the required driving maneuver, but delegate to the driver far-reaching control possibilities for intervening in the otherwise automatically proceeding driving maneuver.
In this case, the space available for maneuvering needs to be detected as exactly as possible, in particular in order to avoid critical situations when maneuvering at only a small distance from obstacles such as e.g. other vehicles.
For this purpose, use is made of distance sensors which are fitted to the vehicle, for example incorporated into the fender, and often operate with ultrasound for the detection of a remaining distance to an obstacle. In this case, ultrasonic signals are emitted and the distance to the reflection location, that is to say the obstacle, is ascertained from the evaluation of the received and reflected signals.
However, the accuracy with which the distance is ascertained is dependent, inter alia, on the sensor technology used. In this regard, by way of example, ultrasonic sensors indeed yield reliable information if the obstacle is situated at a distance outside a near- or short-distance range, that is to say above a minimum distance. For ultrasonic sensors, this is in the range of a few decimeters, typically above 30 cm. If this distance threshold value is undershot, however, no or a less reliable distance indication is ascertained. If a parking maneuver, for example, is then carried out, either automatically or under the control of a driver who relies on visual, acoustic or haptic warning signals from the driving assistance system, this remaining short distance is not utilized for maneuvering, and so in the case of a correspondingly small parking gap a parking maneuver cannot be carried out successfully, even though the remaining distance would possibly suffice to completely carry out the parking maneuver.